PMAC-based Tracking Control System for 8-axis Automated Tape-laying Machine

This article introduces a computer numerical control (CNC)-based open hardware architecture system to realize the special functions of automated tape-laying (ATL) in a numerical control system. It associates a programmable multi-axis controller (PMAC) as the motion control unit with programmable numerical controllers (PCL-725, PCL-730) for on-off control. To bring about synchronized movements of the main 5-axis tape-laying head system and the 3-axis ultrasonic tape-cutting sub-system, the tracking-control method associated with time-based mode attributed to PMAC is applied in different cases. In addition, with the goal of realizing real-time tasks in the software system such as synchronizing motion control and on-off control, the real-time Win 2000 system is adopted. As a device driver for PMAC and PCL, a user graphical interface and a numerical control program interpretation module are also designed. This system is helpful to solve complicated problems in designing numerical controls for ATL such as ensuring high requirements for precise machine control and synchronization of motion control and on-off control.     

The Edison infrared space observatory

For five years, theEdison program has had the goal of developing new designs for infrared space observatories which will break the cost curve by permitting more capable missions at lower cost. Most notably, this has produced a series of models for purely radiative and radiative/mechanical (hybrid) cooling which do not use cryogens and optical designs which are not constrained by the coolant tanks. Purely radiatively-cooled models achieve equilibrium temperatures as low as about 20 K at a distance of 1 AU from the sun. More advancedEdison designs include mechanical cooling systems attached to the telescope assembly which lower the optical system temperature to 5 K or less. Via these designs, near-cryogenic temperatures appear achievable without the limitations of cryogenic cooling. OneEdison model has been proposed to the European Space Agency as the next generation infrared space observatory and is presently under consideration as a candidate ESA Cornerstone mission. The basic design is also the starting point for elements of future infrared space interferometers.     

Adiabatic demagnetisation refrigerators for future sub-millimetre space missions

Space worthy refrigeration capable of providing a 100 mK and below heat load sink for bolometric detectors will be required for the next generation of sub-millimetre space missions. Adiabatic demagnetisation refrigeration (ADR), being a gravity independent laboratory method for obtaining such temperatures, is a favourable technique for utilisation in space.We show that by considering a 3 salt pill refrigerator rather than the classic single salt pill design the space prohibitive laboratory ADR properties of high magnetic field (6 Tesla) and a<2 K environment (provided by a bath of liquid⁴He) can be alleviated, while maintaining a sufficient low temperature hold time and short recycle time. The additional salt pills, composed of Gadolinium Gallium Garnet (GGG) provide intermediate cooling stages, enabling operation from a 4 K environment provided by a single 4 K mechanical cooler, thereby providing consumable free operation. Such ADRs could operate with fields as low as 1 Tesla allowing the use of high temperature, mechanically cooled superconducting magnets and so effectively remove the risk of quenching.We discuss the possibility of increasing the hold time from 3 hours, for the model presented, to between 40 and 80 hours, plus reducing the number of salt pills to two, through the use of a more efficient Garnet.We believe the technical advances necessitated by the envisaged ADRs are minimal and conclude that such ADRs offer a long orbital life time, consumable free, high efficiency means of milli-Kelvin cooling, requiring relatively little laboratory development.     

过渡领域三维绕流直接统计模拟位置元法的一种新方案

本文发展了ＤＳＭＣ方法计算三维绕流位置元方法的新方案，其总体方案和实施细节都是在分析和探索的基础上由我们自己提出的，特别还解决了除气动力、矩总体量以外的气动加热和压力分布等局部分布量的计算所提出的新问题。对于表面位置元的标识、分子的进入及与表面碰撞的判断、网格初始划分与调整、分布量计算对模拟过程及信息存贮所提的特殊要求等进行了分析和讨论，并通过与准确结果的比较证明了采用的方案和技术的有效性。     

21世纪AMSS／GNSS空间段发展方向兼论卫星资源国际共享问题

航空移动卫星系统（ＡＭＳＳ）空间段采用单一的ＧＥＯ轨道卫星，未来将有ＭＥＯ和ＬＥＯ轨道卫星加入运行，仍然不排斥ＧＥＯ轨道卫星的使用。全球导航卫星系统（ＧＮＳＳ）空间段采用ＭＥＯ轨道卫星，未来将仍然以ＭＥＯ为主，可能有ＨＥＯ轨道卫星加入运行。２１世纪的空间段将为不同轨道卫星的多星座组合，采用一星多用、星座共用，形成多功能卫星和多功能星座。和平时期卫星资源的国际民间共建共营共享将更为普遍，要有全球观点，国内各行各业要有全局观点，对监测和增强系统统一筹建共用系统，防止分散投资、重复建设     

不同背角的+G作用对跟踪效率的影响

 本文在大型人体离心机上,在不同座椅背角超重条件下,利用补偿跟踪方法对人的跟踪操作效率进行了研究,观察到伴随超重值的改交,被试者的跟踪误差、手控操作动态参数和心理一生理负荷发生了变化。增大座椅背角和使用侧管式抗荷服,对被试者的工作效率有改善作用。这一结果,从人的工作效率的角度,为高性能歼击机超重防护方案的选择提供了客观依据。     

弹塑性接触有限元分析的凝缩法

 解决弹性接触问题可用一种新的弹塑性接触有限元计算方法,即有限元混合法与弹塑性有限元分析的凝缩法结合而成,能显著地节省计算时间。文中对涡轮盘榫槽与叶片榫头的接触问题进行了计算分析。     

空间站的在轨推进剂再加注问题

建立一个永久性空间站,在轨推进剂再加注将是一个十分重要问题。本文评述了国外研制的各种方案,介绍了先进的在轨推进剂再加注技术、特性和可能实施的方案。最后指出了在轨再加注中的一些技术难点。     

军用飞行器航迹规划综述

介绍了军用飞行器航迹规划的基本概念，航迹规划与任务规划的关系，国内外研究现状，存在的问题，论述了航迹规划的基本要求，如导航要求，突防要求，飞行器性能要求及战略和战术要求，最后分析了航迹规划需要解决的威胁建模，航迹规划算法和轨迹跟踪控制等关键技术。     

联合交互式多模型概率数据关联算法

通过对交互式多模型（IMM）算法和概率数据关联（PDA）算法的研究,指出Bar-Shalom和Blom等提出的IMMPDA算法结构和理论上存在的问题。根据全局最优的思想,设计了一个最优波门,从而得到全局最优的量测集合,保证了系统的理论完整性和结构合理性。推导完成了新的联合IMMPDA算法--C-IMMP-DA算法。大量仿真计算验证了C-IMMPDA算法在减少计算量的同时,总体性能上较之原IMMPDA算法有大幅度提高。